Progesterone

Progesterone is a term that is incorrectly used interchangeably to describe both natural bio-identical progesterone and synthetic non- bio-identical derivatives. Synthetic progestins (also called progestogens or progestational agents) are analogues of bio-identical progesterone, and have been developed because they are patentable, more potent, and have a longer duration. Medroxyprogesterone acetate, the most commonly used synthetic progestin, was shown in a large study to cause significant lowering of HDL “good” cholesterol, thereby decreasing the cardioprotective benefit of estrogen therapy. Bio-identical progesterone has not been reported to produce any serious side effects when administered in physiologic doses. However, progestins can have significant and serious side effects at typical doses, including migraine headache, weight gain, mood swings, depression, irritability, acne, menstrual irregularities, and fluid retention. These side effects are a frequent cause for discontinuation of HRT. Only about 20% of women who start synthetic HRT remain on it two years later.

Progesterone:

• is commonly prescribed for perimenopausal women to counteract “estrogen dominance” which occurs when a woman produces smaller amounts of progesterone than normal relative to estrogen levels.
• alone, or combined with estrogen, may improve bone mineral density.
• minimizes the risk of endometrial cancer in women who are receiving estrogen.
• is preferred by women who had previously taken synthetic progestins.
• may enhance the beneficial effect of estrogen on lipid and cholesterol profiles and exercise-induced myocardial ischemia in postmenopausal women (in contrast to medroxyprogesterone acetate).

The benefits of progesterone are not limited to prevention of endometrial cancer in women who are receiving estrogen replacement. Progesterone therapy is not only needed by women who have an “intact uterus”,  but is also valuable for women who have had a hysterectomy. Vasomotor flushing is the most bothersome complaint of menopause, and is the most common reason women seek HRT and remain compliant. For over 40 years, estrogens have been the mainstay of treatment of hot flashes, but transdermal progesterone cream may be effective as well. Women who have had postpartum depression once have about a 68% chance of having it again after another pregnancy, but trials using prophylactic progesterone have shown that it is possible to reduce the recurrence rate to 7%. Other benefits include improved bone density and enhanced glucose utilization.

J Womens Health Gend Based Med. 2000 May;9(4):381-7
JAMA. 1995 Jan 18; 273(3):199-208
J Am Coll Cardiology 36(7), December 2000: 2154-9
Nature Medicine 1997 Mar;3(3): 324-7
J Am Coll Cardiology March 1, 1997: 671-5
J Reprod Med 1999 Feb;44(2 Suppl):180-4
Endocr Rev. 2007 Jun;28(4):387-439